‘Gay Genes’ – homosexuality determined by DNA?

Is our sexual orientation determined by our DNA? Whether there are ‘gay genes’ remains a hot topic since a study in 1993 suggested that homosexuality in men may be linked to specific genetic polymorphisms on the X chromosome. Now, more than 10 years later, these findings have been vindicated in a new study published in the journal Psychological Medicine.

In 1993, research led by Dean Hamer of the US National Cancer Institute found a link between DNA markers in a specific region of the X chromosome and male homosexuality. DNA linkage analysis showed that among 40 pairs of gay brothers, 33 had concordant polymorphic markers in a specific region of the long arm of the X chromosome, distal Xq28. This indicated the co-inheritance of genetic material linked to their sexual orientation – could there be an allele associated to homosexuality, or ‘gay genes’?

x chromosome

Now, confirmation of Hamer’s initial findings implies that there may indeed be a genetic basis to homosexuality in men, in a novel study led by Dr Alan Sanders at NorthShore University HealthSystem research institute . A genome-wide linkage scan of 409 homosexual male sib-pairs has shown genetic linkage in two chromosomal areas: Xq28 and a region of chromosome 8. Clusters of single nucleotide polymorphisms (SNPs) at these regions were shared among the pairs, supporting earlier evidence that specific genetic material is linked to homosexual orientation.

Although this larger study supports previous findings, it is not conclusive proof that genes determine the development of sexuality. However, scientists continue to explore the theory, and it is hoped that similar research involving both men and women will contribute to reducing the stigma that can surround homosexuality.

 

Sanders, A. R. et al. (2014) Genome-wide scan demonstrates significant linkage for male sexual orientation. Psychological Medicine pp1-10

DOI: http://dx.doi.org/10.1017/S0033291714002451 

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Veronica Wignall

Veronica is a Biology graduate from the University of Bristol, she is currently an editorial assistant but hopes to move into science media comms! Follow Veronica on Twitter @vronwig

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